The present invention relates in general to deicing of windshields of road vehicles, and, more specifically, to reduction of energy use in connection with heating the windshield at the park position of a wiper blade.
To improve the performance of windshield wiper blades in cold or freezing weather, a wiper deicer has become a desirable feature. In particular, such a deicer may provide heating to the windshield and to the wiper blades (which may be parked at a wiper park position at a lower edge of the windshield). The applied heat can reduce or eliminate ice and snow buildup on a wiper blade that impairs performance or that necessitates manual cleaning of a wiper blade by a driver.
While a wiper deicer can be activated manually, it may be particularly beneficial in connection with the remote starting of a vehicle so that the vehicle is in a ready state when the driver enters the vehicle. A typical deicer system will automatically turn off after a predetermined time. Although a manual switch is provided for deactivating the deicer, a user may inadvertently forget to turn the system off after sufficient warming has occurred. Automatic turn-on times are typically chosen to keep the deicer activated long enough to complete deicing under the majority of freezing conditions to be expected.
A commonly used source of heat is an electrical resistance heating layer incorporated into or applied onto the windshield and driven by the vehicle electrical system. Heat can also be obtained via a hot air (i.e., defrost) outlet from a cabin HVAC system. Depending on the type of vehicle, the HVAC heat can be derived from an electrical resistance (positive temperature coefficient) heater or as waste heat from an internal combustion engine. In any case, the deicer can consume significant amounts of battery charge.
Automatic deactivation of the deicer after a predetermined amount of time fails to adapt the deicing function to the actual conditions. Thus, known systems may result in excessive battery discharge if left on too long or may result in insufficient deicing if turned off too soon. In electric or hybrid-electric vehicles, any excess battery drain becomes especially problematic since the electric driving range of the vehicle may be reduced.